I. Field of the Invention
The present invention relates generally to hot metal forming apparatuses.
II. Description of Related Art
There are many industrial applications in which a very hard component is required. For example, in automotive vehicles some components, such as the vertical pillars for the automotive vehicle passenger compartment, are typically constructed of high strength, lightweight materials to protect the occupants of the vehicle in the event of a crash and yet not unduly increase the weight of the vehicle.
One common hard material used in automotive applications is martensite, an allotrope of carbon steel. In order to form a martensite component, a sheet stock or blank of carbon-based with boron element steel is first heated to approximately 850-1100° centigrade which is the temperature necessary to transform the metal blank to austenite. Then, while the metal blank is still hot and above a temperature of about 450° centigrade, the metal blank is positioned within a stamping die and the die is closed to mechanically bend and shape the blank to the shape of the desired component which is defined by the facing surfaces of the die. The now formed component is then quenched at a rapid rate sufficient to transform the austenite to martensite. After quenching, the component is removed and allowed to finish cooling in the air to let the chemical change to martensite finish.
While components formed using the hot stamping method exhibit sufficient hardness, the hot stamping method is expensive to perform in a production facility. A great deal of this cost results from the time needed to quench the now formed blank in the die to a sufficiently low temperature to convert or transform the austenite to martensite. Indeed, in the previously known hot forming metal dies, the overall cycle time for quenching the formed parts can require 10 seconds or even more time in a production facility based on the specific profile of the stamped part. Such a long cycle time in some cases requires the use of multiple stamping dies in order to meet production needs.